The present project is designed to determine methods of metabolic protection of the heart during and following ischemic cardiac arrest. Improved cardiac function has been related to increased cardiac glycogen content, effects of glucose and potassium during the arrest period and effects of potassium alone. The above modalities have been studied during standard techniques including moderate hypothemia (30 degrees C) and profound local cardiac cooling. Recent studies have suggested a beneficial effect of an elevated fatty acid level during the aerobic recovery period following ischemic cardiac arrest. Current studies are in progress to test the hypothesis that fatty acids may be an efficient fuel for the heart during this critical metabolic period.